1. Field of the Invention
The present invention relates to a puncture difficulty evaluating device (a device to evaluate difficulty in puncture) which, when making an injection or the like in an arm of a patient, for example, evaluates the difficulty of puncture for a site in the arm to be punctured with the injection needle.
2. Description of the Related Art
In recent years, with the medical progress, the changes of the medical environment or the like, intravascular injections including intravenous injection and intraarterial injection have been increasingly used both for patients in a serious or emergency condition and patients in a chronically debilitated condition. The primary reasons for this are as follows.
(1) Many drugs are much more effective in the case of intravascular injection or continuous intravenous drip infusion than in the case of oral administration (impossible for patients in a serious condition) or subcutaneous injection. For example, this holds true for administration of cardiotonic drugs, hypertensive drugs, antihypertensive drugs, anticoagulant drugs, antibiotic drugs or the like, fluid infusion, alimentation or the like.
(2) Keeping venous route (locating and securing) is essential for major operations, treatments in ICUs or CCUs or the like. In many cases, if intravascular injection is urgently needed in the cases described in (1), peripheral vessels may have collapsed because of a pressure reduction or a reduction of blood flow and any injection cannot be made thereto. Therefore, before the patient is in an emergency condition, an appropriate peripheral vessel has been selected and a normal saline solution is continuously infused thereto, thereby providing for an emergency.
(3) Medical care for elderly people. In particular, debilitated elderly patients, patients with a cerebral vascular accident or the like are not capable of oral administration of drugs. Therefore, a continuous intravenous drip infusion is often used.
In addition, the cases (4) and (5) described below are not injection, but require puncture on a blood vessel. They are often performed in the clinical setting.
(4) Dialysis. Dialysis has been increasingly conducted. In dialysis, blood is led from an artery in the inner side of a bent elbow of a patient to a dialysis unit, and the blood after dialysis is returned to a vein in the same area. Here, to prepare the blood circuit, the blood vessels have to be punctured. In not a few cases, an obstruction or the like may occur in the blood circuit, and then, another blood circuit has to be newly prepared by changing the points of puncture. In addition, in many cases, a patient requiring dialysis have to be continuously subject to dialysis throughout his/her life. Therefore, the blood vessel wall and the periphery thereof at the area gradually become thicker and hardened, and thus, it becomes difficult to puncture the blood vessel.
(5) In many cases of cardiac catheterization or the like, the catheter is inserted into the femoral artery or vein. In this process, a mantle tube for guiding the catheter has to be inserted into the blood vessel in the first place. Since the mantle tube is thicker than the injection needle, if the mantle tube is inserted into the blood vessel unskillfully, the blood vessel is damaged heavily. Thus, in not a few cases, bleeding from the damaged blood vessel or the like causes treatments after the prolonged catheterization.
In the cases (4) and (5), puncture has to be carried out particularly accurately, and there is a need for means of facilitating puncture.
As described above, intravascular injection is repeatedly carried out for consecutive days for most inpatients for their respective cases. However, in many cases, in particular in the case of debilitated patients or female patients, a suitable blood vessel is often difficult to find in the body surface. In addition, the blood vessels are thickened and hardened due to scar formations because of injection needle insertions repeated for consecutive days, and thus, in many cases, the injection needle cannot readily reach the inside of the blood vessel even if repeatedly trying to insert the injection needle into the blood vessel. Therefore, the intravascular injection is highly painful to the patients, so that the doctors may often be puzzled what to do, and thus, there is a strong clinical need for measures to overcome such a difficulty.
However, in general, the efforts at developing devices are directed to expensive devices, such as PET and artificial organs, and requirements arising in the clinical setting have received little attention.
In order to improve such a circumstance, the prior art was investigated. However, such a technique that directly tackles the circumstance described above was not found. Techniques found that are considered to be somewhat associated with the present technique are listed in the following.
[Diagnosis of Vascular Hardness]
Conventionally, there has been used a diagnostic approach using an indicator (stiffness parameter) that indicates the healthiness of a blood vessel based on the relation between the diameter change and the pressure change resulting from pulsation of the artery (see non-patent reference 1, for example) or a diagnostic approach using an indicator that indicates a statistic change by aging of the blood vessel diameter (see non-patent references 2 and 3, for example). However, there is not found an approach of diagnosing the degree of hardening of a local site of a blood vessel. Ultrasound backscatter pattern analysis is considered to be effective in diagnosis of a local site of a blood vessel which has been hardened to be difficult to puncture. However, in conventionally tissue characteristic diagnostic approaches, backscatter pattern analysis is mainly carried out in vitro. As an in vivo approach, there has been an “integrated backscattering method” that diagnoses scarring of the cardiac muscle due to myocardial infarction (see non-patent reference 4, for example). However, this diagnostic approach cannot be applied as it is to evaluate the difficulty of puncture with an injection needle.
[Puncture assistant device]
Conventionally, for ultrasonic puncture assistant devices, ultrasonically guided puncture methods have been established and widely used (see patent references 1 to 3, for example). However, they are directed to objects located deeply below the body surface (kidney, liver, uterus or the like), rather than the blood vessel near the body surface as in the present invention.
Patent Reference 1
Japanese Patent Laid-Open No. 11-151244
Patent Reference 2
Japanese Patent Laid-Open No. 5-168636
Patent Reference 3
Japanese Patent Laid-Open No. 7-184998
Non-Patent Reference 1
Hasegawa M., et al.: Diagnosis of Carotid Arterial Lesions and Its Clinical Application—With Special Reference to Cerebral Circulation, Vol 35, No.6, P349-358, 1995
Non-Patent Reference 2
Yamazaki Y., et al.: Detection of early change in carotid arteriosclerosis by ultrasound high-resolution B-made imaging, Diabetes Journal vol. 23, No. 1, P25-27, 1995
Non-Patent Reference 3
Handa N., et al.: Ultrasonic Evaluation of Early Carotid Atherosclerosis, Stroke, Vol. 21, No.11, P1567-1572, 1990
Non-Patent Reference 4
J. G. Miller, et al.: MYOCARDIAL TISSUE CHARACTERIZATION: AN APPROACH BASED ON QUANTITATIVE BACKSCATTER AND ATTENUATION, IEEE ULTRASONIC SYMPOSIUM P782-793, 1983